Printing machine inverter common fault
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Take the WIFAG OF370 GTD press (using AMK inverter) as an example.
1. The speed of the paper roll motor is fast and slow.
Phenomenon: During the paper-feeding process, the speed of a paper-feeding roller motor is fast and slow, while the rotation speed of other motors is normal.
Analysis: AMK inverter consists of three modules: power module, control module and digital inverter module. The control module receives various instruction information through the field bus, and then sends the result to the digital inverter module through operation, and the digital inverter module controls the internal thyristor circuit according to the operation result, thereby changing the current frequency of the control motor, so that the motor obtains the location The required speed. According to the working principle of the above inverter, it can be speculated that the cause of this fault may have several aspects: the control module has an operation error, the digital inverter module is faulty, and the motor encoder malfunctions so that the feedback speed is wrong.
Exclusion: According to the principle of easy and complicated first, first replace the SERCOS card on the control module, the fault remains, then replace the digital inverter module, and troubleshoot.
2. Folding machine motor speed is abnormal
Phenomenon: When the car is turned, the drum is rotated quickly, then stopped, and the computer reports "overspeed" failure.
Analysis: According to the above phenomenon, it can be judged that there is a problem with the encoder of the motor. The encoder is mounted on the motor shaft. When the motor rotates, the encoder feeds the real-time speed of the motor to the inverter, and then the inverter adjusts the motor speed according to the set value. In the above fault, the motor speed value fed back to the inverter has an error due to the encoder failure, which causes the inverter to erroneously control the motor.
Remedy: Replace the encoder of the motor and troubleshoot.
3. The inverter reports "converter error" error
Phenomenon: A certain inverter suddenly reported "converter error" during the printing process, and all the motors stopped.
Analysis: The cause of such faults is generally found in the control module or digital inverter module of the inverter.
Exclusion: First check the appearance of each module of the inverter, no trace of damage, no abnormal smell; check the wiring of each module is loose, find the data cable plug between the control module and the digital inverter module One end of the control module is loose at a point. Re-tighten the data cable plug and turn it on. Troubleshoot.
4. The inverter cannot be initialized
Phenomenon: The AMK inverter display always shows “1345 system diagnosis” and the program cannot enter the on-screen menu.
Analysis: According to the fault code "1345" check manual, the cause of this fault is the internal error of the control module.
Remedy: Replace the CPU card on the control module and troubleshoot.
5. The brake resistor of the inverter is overheated and smoked.
Phenomenon: During the printing process, the brake resistor of the inverter of the paper frame suddenly emits white smoke.
Analysis: The braking, deceleration and other processes of the motor during the printing process will cause the motor to generate additional energy, which is converted into heat by the braking resistor connected to the control module. If there is a problem with the control module, it will cause problems with the discharge of these energy.
Exclusion: First check the connection between the control module and the brake resistor, the terminal is not loose; then check the voltage of the "RF" input of the control module is normal (the state of the motor will be converted when the "RF" input is high) The monitoring of the device, the energy of the motor can be discharged through the brake resistor. It is found that when the motor is running, the input of "RF" is low, and the connection of the upper level of "RF" is traced. It is found that the CPU card of the KU has no output and is replaced. Troubleshoot after KU's CPU card.
6. When the header is up and down
Phenomenon: During the printing process, the header of a newspaper that has been folded out of the machine will automatically move up or down, but the registration of each color is normal.
Analysis: Since the color registration of the newspaper is normal, only the head of the newspaper is in the position, it can be judged that the motor of the printing pair is operating normally, but the cutting of the folding machine has a problem.
Remedy: First replace the SERCOS card of the folding machine control module, the fault remains; then replace the CPU card of the control module, the fault is still not solved; then replace the digital inverter module of the inverter, troubleshooting.